Radial piston pump and motor device



Ju y 1970 J. TOBIAS 3,520,232

RADIAL PISTON PUMP AND MOTOR DEVICE Filed Aug. l2 1968 3 Sheets-Sheet 1H IXVENTOR. JAROMIR TOBIAS BY WW W- ATTORNEY J. roams 3,520,232

RADIAL PISTON PUMP AND MOTOR DEVICE July 14, 197

Filed Aug. 12, 1968 3 Sheets-Sheet 2 INVENTOR. JAROMIR TOBIAS ATTORNEYJuly 1% 3970 .1. roams 3,520,232

RADIAL PISTON PUMP AND MOTOR DEVICE I Filed Aug. 12, was 3 Sheets-Sheets 1N1 "ENTOR. JAROMIR TOBIAS BY wan/(gm ATTORNEY United States Patent()fice 3,520,232 Patented July 14, 1970 3,520,232 RADIAL PISTON PUMP ANDMOTOR DEVICE Jaromir Tobias, Box 141, RD. 2, Rhinebeck, NY. 12572 FiledAug. 12, 1968, Ser. No. 751,801 Int. Cl. F04b I/IO, 9/04, 49/00 US. Cl.9l--495 7 Claims ABSTRACT OF THE DISCLOSURE A radial piston pump ormotor including a pintle shaft, a cylinder block rotatable about thepintle shaft, and a reaction ring chassis shiftable transversely of thepintle shaft, a ring assembly rotatably mounted on the chassis, and aseries of piston-reaction ring segments carried by said ring assembly tobe movable relative to each other and the ring assembly, said segmentsincluding piston members extending radially into the bores of the block,the piston members including parti-spherical piston heads to permit arelative tilting of the pistons within the bores.

BACKGROUND OF THE INVENTION Field of the invention This invention is inthe field of radial piston pumps and motors.

The prior art Radial piston pumps and motors typically comprise a pintleshaft, a cylinder block rotatable about the shaft, including a series ofradially directed bores, the bores being connected to the dischargeareas of the pintle shaft during rotation by radially directed fluidpassages. Pistons are mounted within the bores for radial shiftingmovement, the distal ends of the pistons being engaged against asurrounding reaction ring, the axis of which reaction ring may bedisplaced from the axis of rotation of the block. The outer ends of thepistons, in certain constructions, are not directly engaged by thereaction ring, the pistons in such instances being provided with pivotalconnections to piston shoes, which shoes, in turn, slide against andengage the surrounding reaction ring.

In such constructions, the reaction ring rotates with the block andinduces an inward and outward movement of the pistons. Where the deviceis used as a motor, fluid under pressure is introduced to the supplyarea of the pintle shaft and is taken from the discharge area, inducingrotation of the block. Where the device is used as a pump, the block isrotated, causing fluid under pressure to be expressed through thedischarge area of the pintle shaft.

In most of the units heretofore known, the piston heads are cylindrical,the length of the cylindrical piston portions in slidable engagementwith the cylinder walls varying with the requirements of the particularpump or motor.

The use of a short length piston has been found undesirable since thereis always a tilting force exerted against the pistons by reason of theoutward pressure of the outer end of the pistons against the reactionring which is angularly related to the piston axis at all but twopositions during the rotative cycle. In a short piston section, theeffect of this torque is magnified by the relatively high leveragefactor and communicated to the walls of the cylinder bores, drasticallyshortening the life of the piston and the cylinder.

In certain devices, elongated cylindrical pistons have been employed butthe use of these devices involves other drawbacks. Specifically, wherean elongated piston is employed, lubrication throughout the length ofthe piston becomes a problem since normal leakage about the periphery ofthe piston is effective to lubricate a portion only of the length of thepiston. Similarly, the use of an elongated piston will obviouslyincrease the over-all size of the radial piston device of a givendisplacement.

Attempts have been made to employ pistons having parti-spherical headportions. Such parti-spherical piston heads provide the advantages ofshort contact length of the cylinders, thus reducing piston-cylinderlubrication problems. Also, the problem of undue wear of the cylinderbores is avoided, since the pistons are free to tilt within a limitedrange. These advantages are theoretically available without undulyenlarging the over-all diameter of the pump or motor. Heretofore,however, despite the apparent advantages, no device employing thespherical piston head configuration has achieved significant commercialsuccess. Such failure is engendered by the ancillary disadvantages ofcomplex piston-reaction ring connections required by priorconstructions, the failure of such devices to exert the torquegenerating forces at the exact desired vectoral directions, difficultiesin replacing one or more of the pistons in case of failure, and likeproblems.

A particular problem unsolved by any prior pump or motor is the highfriction losses at the piston-reaction ring junction. Lubrication inthis area is often provided by controlled leakages through passages inthe pistons and and piston slippers, which introduce a film or oilbetween the piston slippers and the reaction ring. While the losseswhich inhere in utilizing such controlled lubrication are individuallyrelatively small, they are collectively significant since elficiencyloss is measured as a multiple of the losses of each component of thesystem. -In many instances, such lubrication is effected through minutepassages formed in the length of the pistons and piston slippers, whichpassages communicate with fluid in the cylinder proper. In addition tothe difliculty of conducting oil through such passages to the reactionring, there exists the possibility that small quantities of impuritiesor grit may be lodged in the passages, to reduce or eliminate the flowof lubricant. In this connection it should be appreciated the lubricantmust be admitted to the area between the piston and the reaction ringunder high pressure since the considerable centrifugal force exerted bythe piston against the reaction ring constantly tends to drive thelubricant out from between the noted parts.

SUMMARY OF THE INVENTION A radial piston pump or motor comprising apintle shaft having a fluid supply and discharge areas, a cylinder blockhaving radially directed cylinder bores, passages communicating thebores with the supply and discharge areas sequentially during rotation,a reaction ring chassis shiftable transversely of the pintle shaft,including a ring assembly rotatable relative to the chassis, the devicebeing particularly characterized by a series of piston-reaction ringsegments movable relative to each other and mounted on the ring forangular or arcuate movement about the axis of the rings, the segmentsincluding piston members aflixed thereto and terminating inparti-spherical piston heads disposed in sealing relation of thecylinder bores.

The segments may be individually mounted and dismounted, and may movetoward and away from each other in a plane perpendicular to the axis ofthe pintle shaft in the course of rotation, while at all timesmaintaining the pistons perpendicular to the axis of rotation of therings, whereby the force vectors of the pistons are at all times alignedfor optimum efficiency.

It is therefore an object of the invention to provide an improved radialpiston pump or motor having segmented piston-reaction ring segmentsemploying parti-spherical piston heads.

It is a further object of the invention to provide a device of the classdescribed which is light weight and of reduced outside diameter ascompared with comparable displacement pumps and motors heretofore known.

A further object of the invention is the provision of a device of theclass described which may be readily manufactured and assembled andwherein replacement of individual piston-reaction ring segments may beeffected without disassembly of the entire device.

A further object of the invention is the provision of a device of theclass described wherein forces exerted by or against the pistons are atall times aligned in a direction to operate with utmost efficiency.

It is a further object of the invention to provide a pumpmotor of thetype described wherein the friction between the pistons and cylinders isgreatly reduced.

Still a further object of the invention is the elimination of thedifiicult lubrication problems resulting from the requirement ofconducting lubricant under high pressure to the area between the pistonhead or piston slipper and the reaction ring, a position which, in allprior known devices of this sort, is a considerable radial distance fromthe pintle shaft.

To attain these objects and such further objects as may appear herein orbe hereinafter pointed out, reference is made to the accompanyingdrawings, forming a part hereof, in which:

FIG. 1 is a vertical sectional view through a hydraulic pump or motor inaccordance with the invention, certain details of the apparatus beingdepicted in simplified form to facilitate an understanding of theinvention;

FIG. 2 is a discontinuous section taken on the line 2-2 of FIG. 1;

FIG. 3 is a section taken on the line 33 of FIG. 2.

In accordance with the invention, is a pintle shaft having fluid inputand output conduits 11, 12, which may be connected either to a source offluid under pressure and a reservoir, where the device is used as amotor, or to a hydraulic motor, where the device is used as a pump.

The pintle shaft is provided with laterally open discharge and supplyareas 13, 14, separated by diametrically opposed lands 15, 16 in a wellknown manner. The pintle shaft in the illustrated embodiment is providedwith a continuous cylindrical portion 17 at its innermost end fordefining a seal. A cylinder block assembly 18 is mounted for rotation onthe pintle shaft.

In the device of the illustrated embodiment, the block 18 is disclosedto comprise a hollow shell, for purposes of lightness, it beingrecognized that the conventional solid casting having radially directedcylinder bores may be substituted for the shell, where lightness is nota consideration.

The block 18 is provided with seal areas 19, 20 engaged against solidperipheral areas of the pintle shaft axially displaced from the fluidsupply-discharge areas, which seal areas may incorporate any usual formof rotary seal 20.

The block includes an end Wall 21 connected to an output or input shaft22, as by a pair of machine screws 23 (one only being illustrated)displaced from the center of the shaft.

A series of radially directed cylinder bores 24 (seven in theillustrated embodiment), are formed in the block. In the usual manner,fluid in the discharge and supply areas 13 or 14 is communicated to thebores 24 through flow passages 25 extending between the cylindricalbores and the supply and discharge areas of the pintle shaft.

Preferably, to obtain highest flow efficiency and to secure the otheradvantages which are enumerated in my US. Pat. No. 3,345,916 of Oct. 10,1967, the supply passages 25 are configurated in the manner set forth insaid patent, i.e. they are elongated in the direction of the axis of thepintle shaft and foreshortened in the angular direction at the pintleshaft, and grow progressively shorter and wider and merge smoothly withthe cylinder bores 4 at the area radially outwardly spaced from thepintle shaft.

A reaction ring chassis 26 is supported on the frame of the device (notshown) in a manner to permit lateral movement of the chassis withrespect to the pintle shaft within the limits permitted by theeccentricity slots 27, 28 formed at the opposed ends of the chassis. Itwill be understood that lateral movement may be applied to the chassisby any suitable manual or automatic means. For purposes of illustration,the apparatus for imparting lateral movement is depicted as anadjustment lever 29 mounted on a fixed fulcrum pin 30. The lower end ofthe lever 29 carries a bifurcated yoke 31 which surrounds drive pin 32on the chassis, it being understood that pivotal movement of the leverabout the pin 30 will cause a side-to-side adjustment of the chassis.

The chassis is provided with a spaced pair of rings 33, 34, separatedfrom the circular periphery of walls 35, 36 forming the chassis 26 byroller bearing assemblies 37, 38.

The apparatus, to the extent heretofore described, is essentiallyconventional in most of its details.

To the rings 33, 34 are anchored a series of pistonreaction ringsegments 39 which are generally U-shaped in vertical section (see FIG.2), the U-shaped elements being defined by generally trapezoidal sidelegs 40, 41, the outer ends of which legs are linked by arcuate bridgingelements 42. The legs 40, 41, at their innermost radial ends 43, arearcuate, to conform to the radius of curvature of the outer periphery ofthe rings 33 and 34.

The ends 43 are enlarged in the direction of the axis of the pintleshaft in comparison to the thickness of the major portion of the legs40, 41, defining radially outwardly directed arcuate shoulders 44, 45.

The legs of the piston-reaction ring segments are maintained injuxtaposition to the outer periphery of the rings 33, 34 by inner andouter arcuate attachment fixtures 46, 47. The attachment fixtures aregenerally L-shaped in section, including inwardly directed, arcuateoverlap shoulders 48, 49, respectively, disposed in mating complementalrelation to the outwardly directed shoulders 44, 45, respectively,defined by the enlargement portion 43 at the inner ends of the legs. Theradii of curvature of the inturned portions 48, 49 and the shoulders 44,45 are the same, so as to provide a smooth mating alignment to theseparts.

The legs 40, 41 of the piston-reaction ring segments are secured to therings 33, 34 against relative radial outward movement by cross pins 50which pass through aligned apertures in the inner and outer fixtures 46,47 and in the rings 33, 34. The cross pins 50 have thus an enlarged head51 lying against the inner and outer segments 46, 47, the shank 52 ofthe pins extending through the aligned apertures in the inner segment46, ring 34, outer segment 47, and a washer 53. Cotter pins 54 or likesecuring members may be passed through apertures formed in the outerends of the pins 50 to maintain the pins in the desired position. Aswill be best observed from FIG. 1, preferably at least two pin membersare employed to hold each pair of fixtures 46, 47.

From the foregoing description, it will be observed that the arcuateenlargement 43 at the innermost ends of the legs 40, 41 prevent the legsfrom moving radially inwardly by engagement with the outer periphery ofthe rings 33, 34, and from moving radially outwardly by the overlyingarcuate shoulders 48, 49 of the fixtures 46, 47 secured to said rings.

It will further be observed that the segments 39 may be moved angularlyrelatively to the rings by the above noted arrangement so that adjacentpiston-reaction ring segments 39 are enabled to approach and retreatfrom each other in the course of rotary movement, such approach andretreat travel being confined with a plane perpendicular to the axis ofrotation of the rings 33, 34.

It will be understood that the leg portions of all of thepiston-reaction ring segments are secured to the rings in a similarfashion.

It will be further appreciated that while a specific form of attachmentconnection between the piston-reaction ring segments and rings has beenillustrated, enabling angular relative movement while preventing radialrelative movement of the noted parts, various other forms of connectionsfor accomplishing this end will occur to the skilled artisan. Forinstance, and without limitation, it will be appreciated that, ratherthan providing separate fixtures, a single annular disk providing atrackway engaging the enlargements of the legs will be effective for theintended;

purpose.

As a further variation, one or more roller bearmgs may be interposedbetween the piston-reaction ring segments and the rings 33, 34, ratherthan relying upon the arcuate mating bearing surfaces previouslydescribed. Thus, for instance, the rings may be provided with outwardlydirected flanges and the reaction ring segments may be provided withroller bearing components which engage against the inwardly directedsurfaces of the flanges, the above structure being mentioned by way ofexample only.

From the bridging portions 42 of the piston-reaction ring segments thereextend radially inwardly directed tubular piston rods 55. It will beunderstood that while the piston rods 55 have been shown as integralwith the bridging portion 42, it is altogether feasible to provide areplaceable connection wherein the rod is removably secured to thebridging element.

The radial innermost ends of the rods 55 are provided with piston heads56, the peripheries of which heads are parti-spherical in section. Theparti-spherical plston heads permit relative tilting movement of thepistons within the bores 24, the parti-spherical nature of the headsassuring a sealed condition of the bores throughout all tiltedpositions.

The operation of the device will be evident from the foregoingdescription. Assuming that the unit is to be used as a pump, the shaft22 is connected to a source of rotative power, thus to drive thecylinder block 18 about the pintle shaft. The rotation of the block willcause a concomitant rotation of the rings 33, 34 and the reaction ringsegments 39. When the adjustment lever 29 is arranged so that the axisof rotation of the rings 33, 34 is in alignment with the axis of thepintle shaft, no inward or outward movement of the pistons relative tothe cylinder bores will be experienced and no pumping action will takeplace. Also, in such condition the segments 39 will be equally spacedfrom each other throughout the entire rotation of the device.

When the chassis 26 is shifted laterally by means of the adjustmentlever 29 so as to displace the axis of the rings to one or the otherside of the axis of the pintle shaft, an inward and outward sequentialmovement of the pistons will result, due to the eccentricity of therings relative to the pintle shaft. The inward and outward movement ofthe pistons will create a discharge area of one or the other of theareas 13 or 14 selectively, according to which side of the axis of thepintle shaft the chassis has been shifted.

When the device is used as a motor, as will be readily understood, fluidunder pressure is admitted to one of the areas 13 or 14, including anoutward movement of the pistons which is translated to a rotary movementof the block and drive shaft 22, the direction of rotation being afunction of which of the areas 13 or 14 is connected to the pressureconduit and the direction of eccentricity.

As best understood from FIG. 3, it will be appreciated that the axes ofthe pistons are maintained at all times in radial alignment with thecenter C or axis of rotation of the rings 33, 34.

As will be further appreciated from FIG. 3, when an eccentricity isapplied to the rings, the axes of the pistons are displaced from theaxes of the cylinder bores (except at two points during the rotation ofthe device, i.e. when the axes of the pistons and cylinders are inalignment with a line LL extending through the axis of the pintle shaftC and the axis of rotation C of the rings), such displacement or tiltingmovement being permitted by the parti-spherical interfit of the pistonheads 56 and the cylinder bores 24.

In the course of such tilting movement, the pistonreaction ring segmentswill move toward and away from each other, the closest point of approachbetween adjacent segments being reached when the adjacent segmentscrossthe line LL at the side remote from the direction of displacementof the center C from the center C, and vice versa.

The amount of eccentricity permitted should be calculated to preventinterference between the sides of the piston rods 55- and the bores 24of the block, it being appreciated that the greater the eccentricity,the greater the separation and approach of the piston-reaction ringsegments and, hence, the greater the tilting of the pistons in thecylinders.

From the foregoing, it will be evident that there is described animproved radial piston pump or motor having multiple advantages overradial piston pumps or motors heretofore known. The unit may be readilyassembled and disassembled for replacement of an individual reactionring-piston segment, for instance, without the necessity fordisassembling the remaining segments. By reason of the fact that theconventional circumferential reaction ring is not employed, the over-alldiameter of the unit will be reduced by a considerable factor and theunit will be lighter in weight.

Further, since no circumferential reaction ring in the conventionalsense is employed, the centrifugal forces developed within the unit willbe reduced.

Also, lubrication is facilitated by avoiding the necessity oftransporting lubricating fluid under pressure into space between theouter-most ends of the pistons and the reaction rings, as is required inall prior known radial piston devices.

Since, as noted previously, the piston axis must always be preciselyaligned with the center of the rotating rings 33, 34, the force vectoralfecting the pistons will always be aligned and exerted in the mostefficient manner possible. In contrast, in the typical radial pistondevice, the axes of the pistons are radially directed with respect tothe axis of the cylinder block. This requires that the end of the pistonor the piston shoe engage against the reactron rmg at an angle withrespect to the reaction ring, rather than perpendicular to the engagedportions of the reaction ring. Such angular relation of the partsinduces a tilting moment in the pistons, with the result that a purelyradial force is not applied.

As previously explained, the tilting moment results in increased wear onthe sides of the pistons and cylinder bores as well as at the area ofengagement between the piston heads and the reaction ring.

While in the illustrated embodiment the piston-reaction rmg segments areshown as essentially integral components comprising integral legportions 40 and 41 and bridging portion 42, it will be evident thatthese elements may be comprised of separate parts, subsequentlyintegrated by machine screws, cross pins, etc.

It will be further evident that variations in structure may be made inthe noted device without departing from the spirit of the invention and,accordingly, the invention is to be broadly construed within the scopeof the appended claims.

Having thus described the invention and illustrated its use, what isclaimed as new and is desired to be secured by Letters Patent is:

1. In a radial piston pump or motor comprising a pintle shaft havingfluid supply and discharge areas, a cylinder block rotatably mounted onsaid shaft having radially directed cylinder bores and passagesconnecting said bores with said areas, and a chassis surrounding saidpintle shaft and movable transversely with respect thereto, theimprovement which comprises a spaced pair of rings at opposite sides ofsaid block mounted on said chassis for rotation about a common axis, aseries of generally U-shaped piston assemblies, in number correspondingto the number of said bores, mounted on said rings, each said assemblycomprising a spaced pair of legs, a leg of each said assembly beingmovably connected to a dif ferent one of said rings for sliding movementrelative to said rings in an arcuate path concentric with the axis ofrotation of said rings, a bridging member joining the ends of said legsremote from said rings spaced radially outwardly of said block and apiston member rigidly fixed to and extending radially from said bridgingmember into a bore of said block, said piston member including aparti-spherical piston head disposed in sealing relation of said boreand tiltable relative to said bore.

2. A device in accordance with claim 1 wherein said rings and the legsof said piston assemblies include complemental arcuate bearing surfaces.

3. A device in accordance with claim 2 and including fastener means forlinking together said piston assemblies.

and rings against relative radial movement, while permitting angularmovement of said parts.

4. A device in accordance with claim 3 wherein each said leg portionincludes an outwardly directed arcuate surface concentric with the axisof said rings, said fastener means comprising arcuate segments removablysecured to said rings and having inwardly directed arcuate bearingsurfaces in outwardly lapping, slidable engagement with the outwardlydirected arcuate surfaces of said leg portions.

5. In a radial piston pump or motor comprising a pintle shaft havingfluid supply and discharge areas, a cylinder block rotatably mounted onsaid shaft and having radially directed cylinder bores and passagesconnecting said bores with said areas, a ring chassis surrounding saidpintle shaft and movable transversely with respect thereto, theimprovement which comprises a bearing ring assembly rotatably mounted onand surrounding said chassis, said ring assembly being rotatablerelative to said chassis about an axis parallel with the axis of saidshaft, a plurality of reaction ring segments, mounting means connectingsaid segments to said ring assembly to permit relative sliding movementof said segments and ring assembly in an arcuate path concentric withthe axis of rotation of said ring assembly, while limiting relativeradial movement of said parts, a piston member fixed to each of saidsegments against angular movement and extending radially inwardly towardthe axis of said ring, the inner ends of said piston members beingdefined by parti-spherical piston heads disposed in sealing relation ofsaid bores and tiltable relative to said bores.

6. A device in accordance with claim 5 wherein said mounting meanscomprises complemental arcuate hearing portions on said ring assemblyand said segments.

7. A device in accordance with claim 6 wherein said mounting meansincludes a segment removably secured to said ring assembly and having aninwardly directed arcuate surface in outward lapping engagement of acomplemental, outwardly directed bearing surface formed on said reactionring segment.

References Cited UNITED STATES PATENTS 1,243,494 10/ 1917 Donning 912042,510,247 6/1950 Parenti 230177 3,107,622 10/1963 Von Soden l031613,274,946 9/1966 Simmons 10316-1 3,345,916 10/1967 Tobias 103161 FOREIGNPATENTS 232,373 2/ 1924 Great Britain.

WILLIAM L. FREEH, Primary Examiner U .5. Cl. X.R.

